Conventionally, when manufacturing ICs, electronic components, precision machinery components, optical components, and the like, precision cleaning of components has been widely performed by using a fluorine-based solvent in order to remove flux, a machining oil, wax, a release agent, dust, and the like adhering to the components. Further, in a method in which a composition obtained by dissolving various coating film forming components such as a lubricant in a solvent is applied on a surface of an article, and then the solvent is evaporated to form a coating film, it has been known to use a fluorine-based solvent as the solvent.
As the above-described fluorine-based solvent, chlorofluorocarbon (hereinafter, referred to as “CFC”), hydrochlorofluorocarbon (hereinafter, referred to as “HCFC”), and so on are used because they have high solubility with respect to nonvolatile compounds such as a machining oil and a lubricant, have incombustibility and low toxicity, have excellent stability, do not encroach on a base material of metal, plastic, elastomer, or the like, and have excellent chemical and thermal stability.
However, because CFC and HCFC are chemically quite stable, they each have a long lifetime in the troposphere after vaporization, and diffuse and reach the stratosphere. For this reason, there is a problem that CFC or HCFC reached the stratosphere is decomposed by ultraviolet rays to generate chlorine radicals, which deplete an ozone layer.
As a solvent which does not exert an adverse effect on the ozone layer, perfluorocarbon (hereinafter, referred to as “PFC”), hydrofluorocarbon (hereinafter, referred to as HFC), hydrofluoroether (hereinafter, referred to as HFE), and the like are known. However, because HFC and PFC have a large global warming potential, they are regulation object substances in the Kyoto Protocol. Further, HFC, HFE, and PFC have problems in that they have low solubility of the nonvolatile compounds.
As a solvent which does not exert an adverse effect on the global environment, has low toxicity, and has excellent solubility of the nonvolatile compounds, trans-1,2-dichloroethylene (trans-CHCl═CHCl, which is also referred to as “tDCE”, hereinafter) is known. However, tDCE has an inflammation point, so that it is difficult to be used alone.
Accordingly, it has been proposed to prepare an azeotropic or azeotropic-like composition by combining tDCE and HFE having no inflammation point, and use this composition for cleaning and the like as an incombustible solvent composition. For example, Patent Reference 1 (JP-B No. 2879847) describes an azeotropic or azeotropic-like composition consisting of tDCE and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (CF3CH2OCF2CF2H, which is also referred to as “HFE-347pc-f”, hereinafter). Further, Patent Reference 2 (JP-B No. 4556669) describes a solvent composition containing an azeotropic or azeotropic-like composition consisting of tDCE, HFE-347pc-f, and methanol, ethanol or 2-propanol.